Multiple-primary-color liquid crystal display device

ABSTRACT

A multi-primary-color liquid crystal display device that can get a display operation done more smoothly and with higher definition than a conventional one is provided. 
     A multi-primary-color liquid crystal display device according to the present invention is adapted to conduct a display operation in at least four primary colors. The device has a plurality of pixels that form at least two different types of subsets. The device can perform rendering processing in which at least one of the pixels that form a first one of the at least two different types of subsets lends a luminance to a second type of subset. Each pixel includes a first subpixel and a second subpixel that could have mutually different luminances. The second type of subset borrows a luminance from one of the first and second subpixels of the at least one pixel that has the higher luminance.

TECHNICAL FIELD

The present invention generally relates to a liquid crystal displaydevice and more particularly relates to a multi-primary-color liquidcrystal display device for conducting a display operation using four ormore primary colors.

BACKGROUND ART

Liquid crystal display devices are currently used in a variety ofapplications. In a general display device, one picture element consistsof three pixels respectively representing red, green and blue, which arethe three primary colors of light, thereby conducting a displayoperation in colors.

A conventional liquid crystal display device, however, can reproducecolors that fall within only a narrow range (which is usually called a“color reproduction range”), which is a problem. FIG. 81 shows the colorreproduction range of a conventional liquid crystal display device thatconducts a display operation using the three primary colors.Specifically, FIG. 81 shows an xy chromaticity diagram according to theXYZ color system, in which the triangle, formed by the three pointscorresponding to the three primary colors of red, green and blue,represents the color reproduction range. Also plotted by crosses x inFIG. 81 are the colors of various objects existing in Nature, which weredisclosed by Pointer (see Non-Patent Document No. 1). As can be seenfrom FIG. 81, there are some object colors that do not fall within thecolor reproduction range, and therefore, a liquid crystal display devicethat conducts a display operation using the three primary colors cannotreproduce some object colors.

Thus, to broaden the color reproduction range of liquid crystal displaydevices, a technique that increases the number of primary colors usedfor display purposes to four or more has recently been proposed. Forexample, Patent Document No. 1 discloses a liquid crystal display devicein which one picture element P consists of six pixels R, G, B, Ye, C andM representing the colors red, green, blue, yellow, cyan and magenta,respectively, as shown in FIG. 82. The color reproduction range of sucha liquid crystal display device is shown in FIG. 83. As shown in FIG.83, the color reproduction range, represented by a hexagon of which thesix vertices correspond to those six primary colors, covers almost allobject colors. By increasing the number of primary colors for use indisplay in this manner, the color reproduction range can be broadened.

Patent Document No. 1 also discloses a liquid crystal display device inwhich one picture element consists of four pixels representing thecolors red, green, blue and yellow and a liquid crystal display devicein which one picture element consists of five pixels representing thecolors red, green, blue, yellow and cyan. In any case, by using four ormore primary colors, the color reproduction range can be broadenedcompared to conventional liquid crystal display devices that use onlythe three primary colors for display purposes. Such liquid crystaldisplay devices that conduct a display operation using four or moreprimary colors will be collectively referred to herein as“multi-primary-color liquid crystal display devices”.

In order to further improve the display quality of suchmulti-primary-color liquid crystal display devices, other techniqueshave recently been proposed. For example, Patent Document No. 2discloses a technique for representing a brighter color red by providingtwo pixels representing the color red (i.e., first and second red pixelsR1 and R2) for each picture element P in a multi-primary-color liquidcrystal display device as shown in FIG. 84.

-   -   Patent Document No. 1: PCT International Application Japanese        National Stage Publication No. 2004-529396    -   Patent Document No. 2: Pamphlet of PCT International Application        Publication No. 2007-034770    -   Non-Patent Document No. 1: M. R. Pointer, “The Gamut of Real        Surface Colors,” Color Research and Application, Vol. 5, No. 3,        pp. 145-155 (1980)

DISCLOSURE OF INVENTION Problems to be Solved by the Invention

A plurality of pixels of a multi-primary-color liquid crystal displaydevice include at least one pixel representing a different primary colorfrom the three primary colors, and therefore, can form two or moredifferent subsets, each of which can represent the color white. Forexample, each set of pixels of a multi-primary-color liquid crystaldisplay device that conducts a display operation using the six primarycolors of red, green, blue, yellow, cyan and magenta can form a subsetS1 consisting of red, green and blue pixels R, G and B and a subset S2consisting of cyan, magenta and yellow pixels C, M and Ye as shown inFIG. 85. On the other hand, each set of pixels of themulti-primary-color liquid crystal display device disclosed in PatentDocument No. 2 can form a subset S1 consisting of first red, blue andyellow pixels R1, B and Ye and a subset S2 consisting of second red,green and cyan pixels R2, G and C as shown in FIG. 86. By using thesetwo different subsets S1 and S2 as display units, a display operationcan be carried out with even higher resolution.

Nevertheless, since one of those two subsets S1 and S2 consists ofpixels representing different colors from those of the pixels that formthe other subset, the color white represented by one subset S1 does notexactly match the color white represented by the other subset S2. Forexample, in a situation where a white line is displayed by using the onesubset S1 as shown in FIG. 87( a) and in a situation where a white lineis displayed by using the other subset S2 as shown in FIG. 87( b), thewhite lines will have mutually different luminances, chromaticitiesand/or color temperatures.

To overcome such a problem, the present inventors tentatively adjustedthe luminance of the color white that was displayed using one of the twosubsets by lighting some of the pixels included in the other subset at apredetermined luminance. For example, when a white line is displayedusing the subset S2, the first red and blue pixels R1 and B included inthe other subset S1 may be lit at a predetermined luminance as shown inFIG. 88. Then, the difference in luminance, chromaticity or colortemperature between the two white lines displayed by using the twosubsets S1 and S2 would be reduced.

Nevertheless, as can be seen from FIG. 88, if the first red and bluepixels R1 and B, included in the subset S1, were lit, then the whiteline displayed by the subset S2 would seem to have an increased width.As a result, the resolution would decrease and the display operationcould not be carried out smoothly and with high definition.

It is therefore an object of the present invention to get a displayoperation done more smoothly and with higher definition by amulti-primary-color liquid crystal display device.

Means for Solving the Problems

A multi-primary-color liquid crystal display device according to thepresent invention is adapted to conduct a display operation in at leastfour primary colors. The device has a plurality of pixels that form atleast two different types of subsets. The device can perform renderingprocessing in which at least one of the plurality of pixels that form afirst one of the at least two different types of subsets lends aluminance to a second type of subset. Each of the plurality of pixelsincludes a first subpixel and a second subpixel that could have mutuallydifferent luminances. The second type of subset borrows a luminance fromone of the first and second subpixels of the at least one pixel that hasthe higher luminance.

In one preferred embodiment, the subpixel that has the higher luminancein the at least one pixel and that lends a luminance to the second typeof subset is adjacent to the second type of subset.

In this particular preferred embodiment, in dividing each of theplurality of pixels into the first and second subpixels, a patternapplied to a pixel representing a particular primary color is differentfrom a pattern applied to another pixel.

In a specific preferred embodiment, the pixel representing theparticular primary color includes a subpixel that lends a luminance tothe second type of subset.

In another preferred embodiment, the first and second subpixels havemutually different shapes, and a correlation between the luminanceranking of the first and second subpixels and the shapes of the firstand second subpixels in the pixel representing the particular primarycolor is different from another pixel.

In this particular preferred embodiment, the pixel representing theparticular primary color includes the subpixel that lends a luminance tothe second type of subset.

In still another preferred embodiment, a plurality of subsets of thefirst type and a plurality of subsets of the second type are arranged inmatrix.

In a specific preferred embodiment, the first type of subsets and thesecond type of subsets are arranged alternately in a predetermineddirection, and an arbitrary one of the subsets of the second typeborrows a luminance from one of the two subsets of the first type thatare adjacent to itself on one and the other sides thereof, respectively,in the predetermined direction.

In another specific preferred embodiment, the first type of subsets andthe second type of subsets are arranged alternately in a predetermineddirection, and an arbitrary one of the subsets of the second typeborrows a luminance from both of the two subsets of the first type thatare adjacent to itself on one and the other sides thereof, respectively,in the predetermined direction.

In still another preferred embodiment, each of the plurality of pixelsincludes a liquid crystal layer and a plurality of electrodes forapplying an electric field to the liquid crystal layer. The subsets ofthe first type and the subsets of the second type are alternatelyarranged in a predetermined direction. The pixels included in each saidsubset of the first type and the pixels included in each said subset ofthe second type are also arranged in the predetermined direction withintheir subset. The sum of the number of pixels included in each saidsubset of the first type and that of pixels included in each said subsetof the second type is an even number. The direction of the electricfield applied to the liquid crystal layer of each said pixel invertsevery two pixels in the predetermined direction.

In yet another preferred embodiment, the at least four primary colorsinclude red, green and blue.

In this particular preferred embodiment, the at least four primarycolors further include yellow and cyan.

In a specific preferred embodiment, one of the first and second types ofsubsets includes a first red pixel representing the color red, a bluepixel representing the color blue, and a yellow pixel representing thecolor yellow, while the other type of subset includes a second red pixelrepresenting the color red, a green pixel representing the color green,and a cyan pixel representing the color cyan.

In an alternative preferred embodiment, one of the first and secondtypes of subsets includes a red pixel representing the color red, agreen pixel representing the color green, and a cyan pixel representingthe color cyan, while the other type of subset includes a blue pixelrepresenting the color blue and a yellow pixel representing the coloryellow.

In another preferred embodiment, the at least four primary colorsfurther include magenta.

In this particular preferred embodiment, one of the first and secondtypes of subsets includes a red pixel representing the color red, agreen pixel representing the color green, and a blue pixel representingthe color blue, while the other type of subset includes a cyan pixelrepresenting the color cyan, a magenta pixel representing the colormagenta, and a yellow pixel representing the color yellow.

In yet another preferred embodiment, the rendering processing is carriedout so that a difference in luminance, chromaticity and/or colortemperature between respective colors white represented by the first andsecond types of subsets decreases compared to a situation where therendering processing is not carried out.

EFFECTS OF THE INVENTION

A multi-primary-color liquid crystal display device according to thepresent invention has a plurality of pixels that are classified into atleast two different types of subsets, and can perform renderingprocessing in which at least one of the pixels that form a first type ofsubset lends a luminance to a second type of subset. As a result, thedifference in luminance, chromaticity and/or color temperature betweenthe respective colors white represented by the first and second types ofsubsets can be narrowed. Also, in the multi-primary-color liquid crystaldisplay device of the present invention, each pixel includes first andsecond subpixels that could have mutually different luminances, and thesecond type of subset borrows a luminance from one of the first andsecond subpixels that has the higher luminance. That is to say, in themulti-primary-color liquid crystal display device of the presentinvention, a luminance is lent and borrowed on a subpixel-by-subpixelbasis. Consequently, the device of the present invention can get adisplay operation done more smoothly and with higher definition than aconventional device.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates a pixel arrangement for a multi-primary-color liquidcrystal display device 100 as a preferred embodiment of the presentinvention.

FIG. 2 illustrates the pixel arrangement for the multi-primary-colorliquid crystal display device 100 as the preferred embodiment of thepresent invention.

FIG. 3 illustrates an exemplary specific pixel structure for themulti-primary-color liquid crystal display device 100.

FIG. 4 illustrates another exemplary specific pixel structure for themulti-primary-color liquid crystal display device 100.

FIG. 5 is a graph showing how the luminances of the first and secondsubpixels of each pixel change with the voltage in themulti-primary-color liquid crystal display device 100.

FIG. 6 schematically illustrates how to lend and borrow a luminance inthe multi-primary-color liquid crystal display device 100.

FIG. 7 schematically illustrates how to lend and borrow a luminance inthe multi-primary-color liquid crystal display device 100.

FIG. 8 is a graph showing how the Y (luminance) values of the colorswhite represented by subsets S1 and S2 change before and after renderingprocessing (i.e., lending and borrowing a luminance) is carried out.

FIG. 9 is a graph showing how the xy chromaticity values of the colorswhite represented by subsets S1 and S2 change before and after renderingprocessing (i.e., lending and borrowing a luminance) is carried out.

FIG. 10 illustrates what subpixels are lit by lending and borrowing aluminance as shown in FIG. 7.

FIG. 11 schematically illustrates how to lend and borrow a luminance ina multi-primary-color liquid crystal display device, of which no pixelis divided into multiple subpixels.

FIG. 12 illustrates what subpixels are lit by lending and borrowing aluminance as shown in FIG. 10.

FIG. 13 schematically illustrates how to lend and borrow a luminance inthe multi-primary-color liquid crystal display device 100.

FIG. 14 illustrates what subpixels are lit by lending and borrowing aluminance as shown in FIG. 13.

FIG. 15 illustrates the contour of a white line to be seen in thelighting state shown in FIG. 12.

FIG. 16 illustrates the contour of a white line to be seen in thelighting state shown in FIG. 10.

FIG. 17 illustrates the contour of a white line to be seen in thelighting state shown in FIG. 14.

FIG. 18 illustrates, in combination, the contours O1 and O2 shown inFIGS. 15 and 16.

FIG. 19 illustrates, in combination, the contours O1 and O3 shown inFIGS. 15 and 17.

FIG. 20 illustrates a pixel arrangement for a multi-primary-color liquidcrystal display device 200 as another preferred embodiment of thepresent invention.

FIG. 21 schematically illustrates how to lend and borrow a luminance inthe multi-primary-color liquid crystal display device 200.

FIG. 22 schematically illustrates how to lend and borrow a luminance inthe multi-primary-color liquid crystal display device 200.

FIG. 23 illustrates what subpixels are lit by lending and borrowing aluminance as shown in FIG. 22.

FIG. 24 schematically illustrates how to lend and borrow a luminance ina multi-primary-color liquid crystal display device, of which no pixelis divided into multiple subpixels.

FIG. 25 illustrates what pixels are lit by lending and borrowing aluminance as shown in FIG. 24.

FIG. 26 schematically illustrates how to lend and borrow a luminance inthe multi-primary-color liquid crystal display device 200.

FIG. 27 schematically illustrates how to lend and borrow a luminance inthe multi-primary-color liquid crystal display device 200.

FIG. 28 illustrates what subpixels are lit by lending and borrowing aluminance as shown in FIG. 27.

FIG. 29 schematically illustrates how to lend and borrow a luminance inthe multi-primary-color liquid crystal display device 200.

FIG. 30 illustrates what subpixels are lit by lending and borrowing aluminance as shown in FIG. 29.

FIG. 31 illustrates the contour of a white line to be seen in thelighting state shown in FIG. 25.

FIG. 32 illustrates the contour of a white line to be seen in thelighting state shown in FIG. 28.

FIG. 33 illustrates the contour of a white line to be seen in thelighting state shown in FIG. 30.

FIG. 34 illustrates, in combination, the contours O4 and O5 shown inFIGS. 31 and 32.

FIG. 35 illustrates, in combination, the contours O4 and O6 shown inFIGS. 31 and 33.

FIG. 36 schematically illustrates how to lend and borrow a luminance inthe multi-primary-color liquid crystal display device 200.

FIG. 37 schematically illustrates how to lend and borrow a luminance inthe multi-primary-color liquid crystal display device 200.

FIG. 38 illustrates what subpixels are lit by lending and borrowing aluminance as shown in FIG. 37.

FIG. 39 is a graph showing how the Y (luminance) values of respectivecolors white represented by subsets S1 and S2 change before and afterthe rendering processing (in which a luminance is lent and borrowed) isperformed as shown in FIG. 37.

FIGS. 40( a) through (f) illustrate exemplary division patterns forrespective pixels.

FIG. 41 illustrates what should be taken into consideration when therelative positions of a luminance-lending bright subpixel and aluminance-borrowing subset are determined.

FIG. 42 illustrates a pixel arrangement for a multi-primary-color liquidcrystal display device 300 as still another preferred embodiment of thepresent invention.

FIG. 43 schematically illustrates how to lend and borrow a luminance inthe multi-primary-color liquid crystal display device 300.

FIG. 44 schematically illustrates how to lend and borrow a luminance inthe multi-primary-color liquid crystal display device 300.

FIG. 45 is a graph showing how the Y (luminance) values of respectivecolors white represented by subsets S1 and S2 change before and afterthe rendering processing (in which a luminance is lent and borrowed) isperformed as shown in FIG. 44.

FIG. 46 is a graph showing how the xy chromaticity values of respectivecolors white represented by subsets S1 and S2 change before and afterthe rendering processing (in which a luminance is lent and borrowed) isperformed as shown in FIG. 44.

FIG. 47 illustrates what subpixels are lit by lending and borrowing aluminance as shown in FIG. 44.

FIG. 48 schematically illustrates how to lend and borrow a luminance ina multi-primary-color liquid crystal display device, of which no pixelis divided into multiple subpixels.

FIG. 49 illustrates what pixels are lit by lending and borrowing aluminance as shown in FIG. 48.

FIG. 50 schematically illustrates how to lend and borrow a luminance inthe multi-primary-color liquid crystal display device 300.

FIG. 51 illustrates what subpixels are lit by lending and borrowing aluminance as shown in FIG. 50.

FIG. 52 illustrates a pixel arrangement for a multi-primary-color liquidcrystal display device 400 as yet another preferred embodiment of thepresent invention.

FIGS. 53( a) and 53(b) schematically illustrate how to lend and borrow aluminance in the multi-primary-color liquid crystal display device 400.

FIG. 54 schematically illustrates how to lend and borrow a luminance inthe multi-primary-color liquid crystal display device 400.

FIG. 55 is a graph showing how the Y (luminance) values of respectivecolors white represented by subsets S1 and S2 change before and afterthe rendering processing (in which a luminance is lent and borrowed) isperformed as shown in FIG. 54.

FIG. 56 is a graph showing how the xy chromaticity values of respectivecolors white represented by subsets S1 and S2 change before and afterthe rendering processing (in which a luminance is lent and borrowed) isperformed as shown in FIG. 54.

FIG. 57 illustrates what subpixels are lit by lending and borrowing aluminance as shown in FIG. 54.

FIG. 58 illustrates what subpixels are lit by lending and borrowing aluminance as shown in FIG. 54.

FIG. 59 schematically illustrates how to lend and borrow a luminance inthe multi-primary-color liquid crystal display device 400.

FIG. 60 illustrates what subpixels are lit by lending and borrowing aluminance as shown in FIG. 59.

FIG. 61 illustrates what subpixels are lit by lending and borrowing aluminance as shown in FIG. 59.

FIG. 62 illustrates a pixel arrangement for a multi-primary-color liquidcrystal display device 500 as yet another preferred embodiment of thepresent invention.

FIG. 63 schematically illustrates how to lend and borrow a luminance inthe multi-primary-color liquid crystal display device 500.

FIG. 64 illustrates what subpixels are lit by lending and borrowing aluminance as shown in FIG. 63.

FIG. 65 illustrates what subpixels are lit by lending and borrowing aluminance as shown in FIG. 63.

FIG. 66 schematically illustrates how to lend and borrow a luminance inthe multi-primary-color liquid crystal display device 500.

FIG. 67 illustrates what subpixels are lit by lending and borrowing aluminance as shown in FIG. 66.

FIG. 68 illustrates what subpixels are lit by lending and borrowing aluminance as shown in FIG. 66.

FIG. 69 illustrates a pixel arrangement for a multi-primary-color liquidcrystal display device 600 as yet another preferred embodiment of thepresent invention.

FIG. 70 schematically illustrates how to lend and borrow a luminance inthe multi-primary-color liquid crystal display device 600.

FIG. 71 schematically illustrates how to lend and borrow a luminance inthe multi-primary-color liquid crystal display device 600.

FIG. 72 illustrates what subpixels are lit by lending and borrowing aluminance as shown in FIG. 71.

FIG. 73 schematically illustrates how to lend and borrow a luminance inthe multi-primary-color liquid crystal display device 600.

FIG. 74 schematically illustrates how to lend and borrow a luminance inthe multi-primary-color liquid crystal display device 600.

FIG. 75 illustrates what subpixels are lit by lending and borrowing aluminance as shown in FIG. 74.

FIG. 76 indicates the directions of an electric field applied to theliquid crystal layer of each pixel when a dot inversion drive is carriedout in the multi-primary-color liquid crystal display device 600.

FIG. 77 indicates the directions of an electric field applied to theliquid crystal layer of each pixel when a two-source-line inversiondrive is carried out in the multi-primary-color liquid crystal displaydevice 600.

FIG. 78 schematically illustrates how to lend and borrow a luminance inthe multi-primary-color liquid crystal display device 600.

FIG. 79 schematically illustrates how to lend and borrow a luminance inthe multi-primary-color liquid crystal display device 600.

FIG. 80 illustrates what subpixels are lit by lending and borrowing aluminance as shown in FIG. 79.

FIG. 81 shows the color reproduction range of a conventional liquidcrystal display device that conducts a display operation using the threeprimary colors.

FIG. 82 schematically illustrates a conventional multi-primary-colorliquid crystal display device.

FIG. 83 shows the color reproduction range of the multi-primary-colorliquid crystal display device shown in FIG. 82.

FIG. 84 schematically illustrates another conventionalmulti-primary-color liquid crystal display device.

FIG. 85 illustrates two different types of subsets formed by multiplepixels in the conventional multi-primary-color liquid crystal displaydevice shown in FIG. 82.

FIG. 86 illustrates two different types of subsets formed by multiplepixels in the conventional multi-primary-color liquid crystal displaydevice shown in FIG. 84.

FIG. 87( a) illustrates a situation where a white line is displayedusing one of the two different types of subsets and FIG. 87( b)illustrates a situation where a white line is displayed using the othertype of subset.

FIG. 88 illustrates a situation where when a white line is displayedusing one type of subset, some pixels in the other type of subset arelit as supplementary pixels at a predetermined luminance.

DESCRIPTION OF REFERENCE NUMERALS

-   R red pixel-   R1 first red subpixel-   R2 second red subpixel-   G green subpixel-   B blue subpixel-   C cyan subpixel-   M magenta subpixel-   Ye yellow subpixel-   S1, S2 subset-   10 pixel-   10 a first subpixel-   10 b second subpixel-   12 scan line-   14, 14 a, 14 b signal line-   16 a, 16 b TFT-   18 a, 18 b subpixel electrode-   22 a, 22 b storage capacitor-   24 a, 24 b storage capacitor line-   100, 200, 300 multi-primary-color liquid crystal display device-   400, 500, 600 multi-primary-color liquid crystal display device

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, preferred embodiments of the present invention will bedescribed with reference to the accompanying drawings. However, thepresent invention is in no way limited to the specific preferredembodiments to be described below but is broadly applicable to anymulti-primary-color liquid crystal display device in general as long asthe device carries out a display operation in four or more primarycolors.

Embodiment 1

FIG. 1 illustrates a pixel arrangement for a multi-primary-color liquidcrystal display device 100 (which will be simply referred to herein asan “LCD 100”). As Shown in FIG. 1, the LCD 100 includes first and secondred pixels R1 and R2 representing the color red, a green pixel Grepresenting the color green, a blue pixel B representing the colorblue, a yellow pixel Ye representing the color yellow, and a cyan pixelC representing the color cyan. These pixels are arranged in columns androws to form a matrix pattern. More specifically, rows of pixels, ineach of which the first red, yellow and blue pixels R1, Ye and B arearranged cyclically, and rows of pixels, in each of which the secondred, green and cyan pixels R2, G and C are arranged cyclically, arealternately arranged in the column direction. Each pixel includes aliquid crystal layer and a plurality of electrodes for applying anelectric field to the liquid crystal layer.

As shown in FIG. 1, the LCD 100 can conduct a display operation usingthese six pixels, namely, the first and second red pixels R1 and R2, thegreen pixel G, the blue pixel B, the yellow pixel Ye and the cyan pixelC, as the minimum unit of color display (i.e., as a single pictureelement P). This LCD 100 uses a larger number of primary colors fordisplay purposes than a normal LCD that conducts a display operation inthe three primary colors, and therefore, realizes a broader colorreproduction range and can display any of various object colorsinclusively. On top of that, the LCD 100 includes the first and secondred pixels R1 and R2 representing the color(s) red, and therefore, canrepresent a bright color red as disclosed in Patent Document No. 2. Itshould be noted that the colors red represented by the first and secondred subpixels R1 and R2 could be either different from each other oridentical with each other.

Also, as shown in FIG. 2, the pixels of the LCD 100 can form twodifferent types of subsets S1 and S2, each of which can represents thecolor white. One S1 of the two different types of subsets includes thefirst red, yellow and blue pixels R1, Ye and B, while the other type ofsubset S2 includes the second red, green and cyan pixels R2, G and C. Aplurality of subsets of the first type S1 and a plurality of subsets ofthe second type S2 are arranged in matrix. Specifically, a plurality ofsubsets of either the first type S1 or the second type S2 are arrangedin the row direction, while the first and second types of subsets S1 andS2 are arranged alternately in the column direction. In this manner, asmultiple pixels can form first and second types of subsets S1 and S2,the LCD 100 can conduct a display operation with even higher resolutionby using those subsets S1 and S2 as display units.

Nevertheless, the color white represented by the subset S1 does notexactly match the color white represented by the subset S2. That is whyin representing the color white using one of the two different types ofsubsets S1 and S2, the LCD 100 of this preferred embodiment lights atleast one of the pixels included in the other type of subset. In thismanner, if any of the pixels that form one type of subset (which will bereferred to herein as a “first type of subset” for convenience sake) islit as a supplementary pixel when the other type of subset (which willbe referred to herein as a “second type of subset” for convenience sake)displays the color white, then such an act will be referred herein as“the pixel of the first type of subset lending a luminance to the secondtype of subset” or “the second type of subset borrowing a luminance fromthe pixel of the first type of subset”. The LCD 100 of this preferredembodiment carries out such rendering processing so that at least one ofthe pixels included in one of the two different types of subsets S1 andS2 (which will be referred to herein as a “first type of subset”) lendsa luminance to the other type of subset (which will be referred toherein as a “second type of subset”). As a result, the difference inluminance, chromaticity and/or color temperature between the respectivecolors white represented by those two types of subsets can be reduced.

If the rendering processing described above were simply performed, theresolution would decrease as already described with reference to FIG.88. The LCD 100 of this preferred embodiment, however, has a specialtype of arrangement to be described below, and therefore, can minimizethe decrease in resolution even if the rendering processing describedabove is performed.

FIG. 3 illustrates a specific structure for each pixel 10 of the LCD100. As shown in FIG. 3, each pixel 10 includes first and secondsubpixels 10 a and 10 b, which can have mutually different luminances.That is to say, each pixel 10 can be driven so that when a certaingrayscale is displayed, mutually different voltages are applied torespective portions of the liquid crystal layer for the first and secondsubpixels 10 a and 10 b. It should be noted that the number of subpixelsthat a single pixel 10 has (which will also be referred to herein as “apixel division number”) does not have to be two. Optionally, a thirdsubpixel (not shown), to which a different voltage from the one for thefirst or second subpixel 10 a, 10 b can be applied, may be furtherprovided.

If each pixel 10 is divided into multiple subpixels 10 a, 10 b that canhave mutually different luminances, then a mixture of multiple differentγ characteristics will be observed. As a result, the viewing angledependence of the γ characteristic (which is a phenomenon that thecharacteristic when the screen is viewed straight from in front of thepanel is different from the one when the screen is viewed obliquely) canbe reduced. Since the γ characteristic represents the degree ofgrayscale dependence of the luminance displayed, the variation in γcharacteristic according to whether the viewing direction is straight oroblique means that the grayscale display state will also vary accordingto the viewing direction. Such a technique for reducing the viewingangle dependence of the γ characteristic by dividing a single pixel intomultiple subpixels is called a “multi-pixel drive” and disclosed inJapanese Patent Application Laid-Open Publication No. 2004-62146, forexample.

To apply effective voltages of mutually different amplitudes torespective portions of the liquid crystal layer for the first and secondsubpixels 10 a and 10 b, any of various structures as disclosed in notonly Japanese Patent Application Laid-Open Publication No. 2004-62146mentioned above but also Japanese Patent Application Laid-OpenPublications Nos. 2006-39130, 2006-201764, 2007-226242 and so on couldbe used.

For example, the arrangement shown in FIG. 3 may be adopted. In aconventional LCD, a single pixel has only one pixel electrode that isconnected to a signal line via a switching element (such as a TFT). Onthe other hand, the single pixel 10 shown in FIG. 3 includes twosubpixel electrodes 18 a and 18 b that are connected to two differentsignal lines 14 a and 14 b via their associated TFTs 16 a and 16 b,respectively.

As the first and second subpixels 10 a and 10 b form one pixel 10, therespective gates of the TFTs 16 a and 16 b are connected in common tothe same scan line (gate line) 12 and have their ON and OFF statescontrolled in response to the same scan signal. On the other hand,signal voltages (i.e., grayscale voltages) are supplied onto the signallines (source lines) 14 a and 14 b so that the first and secondsubpixels 10 a and 10 b have mutually different luminances.

Alternatively, the arrangement shown in FIG. 4 may also be adopted. Inthe arrangement shown in FIG. 4, the respective source electrodes of theTFTs 16 a and 16 b are connected in common to the same signal line 14.Also, storage capacitors (CS) 22 a and 22 b are provided for the firstand second subpixels 10 a and 10 b, respectively, and connected tostorage capacitor lines (CS lines) 24 a and 24 b, respectively. Each ofthese storage capacitors 22 a and 22 b consists of a storage capacitorelectrode that is electrically connected to the subpixel electrode 18 aor 18 b, a storage capacitor counter electrode that is electricallyconnected to the storage capacitor line 24 a or 24 b, and an insulatinglayer interposed between them (none of those members are shown in FIG.4). The storage capacitor counter electrodes of the storage capacitors22 a and 22 b are independent of each other and are designed so as to besupplied with mutually different voltages (which will be referred toherein as “storage capacitor counter voltages”) through the storagecapacitor lines 24 a and 24 b, respectively. By changing the storagecapacitor counter voltages applied to the storage capacitor counterelectrodes, mutually different effective voltages can be applied torespective portions of the liquid crystal layer for the first and secondsubpixels 10 a and 10 b by utilizing capacitance division.

In the arrangement illustrated in FIG. 3, mutually independent TFTs 16 aand 16 b are connected to the first and second subpixels 10 a and 10 b,respectively, and have their source electrode connected to theirassociated signal lines 14 a and 14 b, respectively. That is whyarbitrary effective voltages can be applied to the respective portionsof the liquid crystal layer for the subpixels 10 a and 10 b. However,the number of signal lines 14 a, 14 b to be provided and the number ofsignal line drivers to be provided both need to be doubled compared to aconventional LCD.

On the other hand, if the arrangement shown in FIG. 4 is adopted, thereis no need to apply mutually different signal voltages to the subpixelelectrodes 18 a and 18 b, and therefore, the TFTs 16 a and 16 b may beconnected in common to the same signal line 14 and may be supplied withthe same signal voltage. That is why this LCD may have the same numberof signal lines 14, and a signal line driver with the sameconfiguration, as the conventional LCD.

FIG. 5 shows how the luminances of the first and second subpixels 10 aand 10 b change with the voltage (which is a signal voltage applied tothe subpixel electrodes 18 a and 18 b) in a situation where thearrangement shown in FIG. 4 is adopted. As can be seen from FIG. 5, eventhough the same voltage is applied to the two subpixels, one subpixelhas a higher luminance than the other. In the following description, theone subpixel with the higher luminance will be referred to herein as a“bright subpixel” and the other subpixel with the lower luminance a“dark subpixel”.

When the LCD 100 of this preferred embodiment performs renderingprocessing, the subset to be a luminance borrower (i.e., the second typeof subset) borrows a luminance from the bright subpixel of a pixelincluded in the subset to be a luminance lender (i.e., the first type ofsubset). That is to say, the pixel in the first type of subset does notlend a luminance by lighting itself entirely but lends a luminance on asubpixel-by-subpixel basis by lighting only one of its two subpixels(i.e., the bright subpixel).

FIGS. 6 and 7 schematically illustrate how to lend and borrow aluminance in that way. In the examples illustrated in FIGS. 6 and 7, thebright subpixel of each pixel is identified by “H” and the dark subpixelthereof by “L”. To minimize a flicker on the screen, the luminanceranking of subpixels (i.e., the order of magnitudes of their luminance)is preferably shuffled as randomly as possible. To realize an idealdisplay condition, most preferred is an arrangement in which nosubpixels of the same luminance rank are adjacent to each other in thecolumn or row direction. That is to say, such subpixels of the sameluminance rank are preferably arranged in a checkerboard pattern asshown in FIGS. 6 and 7.

In the LCD 100 of this preferred embodiment, the subset S2 borrows aluminance from the respective bright subpixels of the first red pixel R1and the blue pixel B included in the subset S1 as indicated by theshadowed arrows in FIGS. 6 and 7. The following Tables 1 and 2 and FIGS.8 and 9 show how the Y values and xy chromaticity values of respectivepixels and the Y values (i.e., luminance values), xy chromaticity valuesand color temperatures of the colors white represented by the subsets S1and S2 change before and after the rendering processing described aboveis carried out. The Y values shown are relative values with the sum ofthe Y values of the two subsets supposed to be 100%.

TABLE 1 Before render- ing Y x y Y(w) x(w) y(w) Tc(w)/K S1 R1 7.9 0.65810.3219 56.0 0.3340 0.2715 5360 Ye 43.1 0.4637 0.5248 B 5.0 0.1471 0.0502S2 R2 7.9 0.6581 0.3219 44.0 0.2842 0.3714 7529 G 21.3 0.2521 0.6579 C14.8 0.152 0.2404 total 100.0 100.0

TABLE 2 After rendering Y x y Y(w) x(w) y(w) Tc(w)/K S1 R1 2.8 (35%)0.6581 0.3219 50.0 0.3224 0.2885 6189 Ye 43.1 0.4637 0.5248 B 4.2 (83%)0.1471 0.0502 S2 (B) 0.85 (17%)  0.1471 0.0502 50.0 0.3083 0.3302 5514R2  7.9 0.6581 0.3219 G 21.3 0.2521 0.6579 C 14.8 0.152 0.2404 (R1) 5.1(65%) 0.6581 0.3219 total 100.0  100.0

Before the rendering processing is carried out, the luminances,chromaticity values and color temperatures of the colors whiterepresented by the subsets S1 and S2 are quite different from each otheras can be seen from Table 1 and FIGS. 8 and 9. However, after therendering processing has been carried out (the first red pixel R1 andthe blue pixel B of the subset S1 respectively lend 65% and 17% of theirown luminance to the subset S2 as can be seen from Table 2), theluminances of the colors white represented by the subsets S1 and S2exactly agree with each other and their differences in chromaticity andcolor temperature have also decreased as can be seen from Table 2 andFIGS. 8 and 9.

In this manner, by carrying out the rendering processing, thedifferences in luminance, chromaticity and color temperature between therespective colors white represented by the two different types ofsubsets S1 and S2 can be narrowed. In the example described above, thedifference in luminance between the colors white is supposed to bedecreased first and foremost by carrying out the rendering processing.However, a higher priority can be given to the difference inchromaticity or color temperature instead. In any case, all of thosedifferences in luminance, chromaticity and color temperature between thesubsets can be narrowed by carrying out the rendering processing.

Next, it will be described with reference to FIG. 10 what subpixels arelit as a result of the rendering processing. Specifically, FIG. 10illustrates what subpixels need to be lit to display a horizontal whiteline on a black background using the subsets S2. In FIG. 10, the openrectangles represent lighted subpixels (i.e., subpixels in non-blackdisplay state), while the shadowed rectangles represent non-lightedsubpixels (i.e., in black display state). As can be seen from FIG. 10,not only entire pixels (i.e., both of their first and second subpixels)in each subset S2 on the row L2 but also some subpixels on the rows L1and L3 are lit so that the rendering processing for lending a luminanceis carried out on a subpixel-by-subpixel basis.

For the purpose of comparison, it will be described what pixels are litin a situation where the rendering processing is carried out on amulti-primary-color liquid crystal display device in which no pixel isdivided into multiple subpixels. For example, if the renderingprocessing in which each subset S2 borrows a luminance from the firstred pixel R1 and the blue pixel B of its associated subset S1 has beencarried out as shown in FIG. 11, lighted pixels will be as shown in FIG.12. As can be seen from FIG. 12, not only all pixels in each subset S2on the row L2 but also some pixels on the row L1 are lit, and therendering processing for lending a luminance has been carried out on apixel-by-pixel basis. And comparing FIGS. 10 and 12 to each other, itcan be seen easily that the white line displayed can look thinner, andthe display operation can get done more smoothly and with higherdefinition, by lending and borrowing a luminance on asubpixel-by-subpixel basis as is done in this preferred embodiment.

In the example illustrated in FIG. 7, the bright subpixels of each pairof first red and blue pixels R1 and B that lend their luminance are bothadjacent to its associated subset S2. In other words, to borrow aluminance from adjacent bright subpixels, each subset S2 chooses eitherthe subset S1 that is adjacent to the subset S2 on one side in thecolumn direction or the subset S1 that is adjacent to the subset S2 onthe other side in the column direction. For example, some subsets S2 onthe row L2 (such as the leftmost and third leftmost subsets S2) borrow aluminance from the subsets S1 on the lower row L3, while the othersubsets S2 on the same row L2 (such as the second leftmost and rightmostsubsets S2) borrow a luminance from the subsets S1 on the upper row L1.To get a display operation done more smoothly and with higherdefinition, the bright subpixels that lend their luminance arepreferably adjacent to each subset of the second type (i.e., each subsetof the second type preferably borrows a luminance from its adjacentbright subpixels).

Nevertheless, the second type of subset (i.e., a subset to be aluminance borrower) does not always have to borrow a luminance from itsadjacent bright subpixels as shown in FIG. 13. In the exampleillustrated in FIG. 13, each subset S2 on the row L2 always borrows aluminance from the bright subpixels of its associated subset S1 on therow L1. That is why some subsets S2 (i.e., the second leftmost andrightmost subsets S2) on the row L2 borrow a luminance from theiradjacent bright subpixels but the other subsets S2 (i.e., the leftmostand third leftmost subsets S2) on the same row L2 borrow a luminancefrom bright subpixels that are not adjacent to themselves.

FIG. 14 illustrates what subpixels will be lit when a luminance is lentand borrowed as shown in FIG. 13. As can be seen from FIG. 14, not onlyentire pixels (i.e., both of their first and second subpixels) in eachsubset S2 on the row L2 but also some subpixels in each subset S1 on therow L1 are lit, and therefore, the rendering processing for lending aluminance has also been carried out on a subpixel-by-subpixel basis.However, unlike the situation shown in FIG. 10, the lighted subpixels inthe subsets S1 include not only ones adjacent to any of the subsets S2but also ones that are not adjacent to any subset S2. Nevertheless, evenif a luminance is lent and borrowed as shown in FIGS. 13 and 14, thedecrease in resolution can still be less significant than a situationwhere a luminance is lent and borrowed on a pixel-by-pixel basis asshown in FIGS. 11 and 12.

Such an effect of minimizing the decrease in resolution will bedescribed more specifically with reference to FIGS. 15 through 19. FIGS.15, 16 and 17 illustrate the contours of the white line to be seen inthe lighting states shown in FIGS. 12, 10 and 14, respectively. On theother hand, FIG. 18 illustrates, in combination, the contours O1 and O2that are shown in FIGS. 15 and 16, respectively, while FIG. 19illustrates, in combination, the contours O1 and O3 that are shown inFIGS. 15 and 17, respectively. FIGS. 15 through 19 also show thecenterline of the row L2.

Comparing the results shown in FIGS. 15 and 16 to each other byreference to FIG. 18, it can be seen that the white line displayed looksthinner by lending and borrowing a luminance on a subpixel-by-subpixelbasis rather than by doing that on a pixel-by-pixel basis. The same canbe said even if the results shown in FIGS. 15 and 17 are compared toeach other by reference to FIG. 19. Consequently, by carrying out therendering processing on a subpixel-by-subpixel basis, the decrease inresolution can be much less significant, and the display operation canget done far more smoothly and with much higher definition, compared toa situation where the rendering processing is carried out on apixel-by-pixel basis.

In addition, comparing the results shown in FIGS. 16 and 17 or the onesshown in FIGS. 18 and 19 to each other, it can also be seen that ifevery bright subpixel to be luminance lender is adjacent to the subsetS2 to be a luminance borrower, not just can the white line displayedlook thinner but also can a sufficient degree of symmetry be kept withrespect to the centerline. That is to say, the bright subpixel to be aluminance lender is preferably one of the first and second subpixels ofa pixel in each subset of the first type (i.e., a subset including thebright subpixel to be a luminance lender) that is located closer (i.e.,adjacent) to its associated subset of the second type (i.e., a subset tobe luminance borrower).

Embodiment 2

FIG. 20 illustrates a pixel arrangement for an LCD (multi-primary-colorliquid crystal display device) 200 as a second specific preferredembodiment of the present invention. Just like the LCD 100 shown in FIG.1, the LCD 200 includes first and second red pixels R1, R2, green pixelsG, blue pixels B, yellow pixels Ye, and cyan pixels C.

In the LCD 200, however, the first red, yellow, blue, second red, greenand cyan pixels R1, Ye, B, R2, G and C are arranged cyclically withinthe same row so that the subsets S1 and S2 alternate with each other inthe row direction. That is why even though a luminance is lent andborrowed between two subsets that are adjacent to each other in thecolumn direction in the LCD 100, a luminance is lent and borrowedbetween two subsets that are adjacent to each other in the row directionin this LCD 200.

FIGS. 21 and 22 schematically illustrate how to lend and borrow aluminance in this LCD 200. First of all, please note that the shape ofthe subpixels that each pixel has in this LCD 200 is different from thatof the LCD 100. Specifically, although each pixel is split in the LCD100 into two rectangular subpixels, each pixel is divided in this LCD200 into an isosceles triangular subpixel, of which the base is definedby one of the two longer sides of the pixel, and a subpixel formed bythe rest of the pixel (i.e., consisting of two right triangle). In thispreferred embodiment, a display operation is conducted by using theformer subpixel as a bright subpixel (identified by “H” in FIG. 21) andthe latter subpixels as dark subpixels (identified by “L” in FIG. 21).

As shown in FIGS. 21 and 22, the subset S2 borrows a luminance from therespective bright subpixels of the first red pixel R1 and the blue pixelB that are included in subsets S1. More specifically, the subset S2borrows a luminance from not only the bright subpixel of the first redpixel R1 belonging to the subset S1 on its right hand side but also thebright subpixel of the blue pixel B belonging to the subset S1 on itsleft hand side. In the LCD 100 of the first preferred embodiment, anarbitrary subset of the second type borrows a luminance from one of thetwo subsets of the first type that are adjacent to itself in one and theother sides thereof in a predetermined direction. On the other hand, inthe LCD 200 of this preferred embodiment, an arbitrary subset of thesecond type borrows a luminance from both of the two subsets of thefirst type that are adjacent to itself in one and the other sidesthereof in another predetermined direction.

FIG. 23 illustrates what subpixels need to be lit to display a verticalwhite line on a black background using the subsets S2. As can be seenfrom FIG. 23, not only entire pixels (i.e., both of their first andsecond subpixels) in each subset S2 on the column C3 but also somesubpixels on the columns C2 and C4 are lit so that the renderingprocessing for lending a luminance is carried out on asubpixel-by-subpixel basis.

For the purpose of comparison, it will be described what pixels are litin a situation where the rendering processing is carried out on amulti-primary-color liquid crystal display device in which no pixel isdivided into multiple subpixels. For example, if the renderingprocessing in which each subset S2 borrows a luminance from the firstred pixel R1 and the blue pixel B of its associated subsets S1 has beencarried out as shown in FIG. 24, lighted pixels will be as shown in FIG.25. As can be seen from FIG. 25, not only all pixels in each subset S2on the column C3 but also some pixels on the columns C2 and C4 are lit,and the rendering processing for lending a luminance has been carriedout on a pixel-by-pixel basis. And comparing FIGS. 23 and 25 to eachother, it can be seen easily that the white line displayed can lookthinner, and the display operation can get done more smoothly and withhigher definition, by lending and borrowing a luminance on asubpixel-by-subpixel basis as is done in this preferred embodiment.

Also, in the example illustrated in FIG. 22, each of the respectiveluminance-lending bright subpixels of the first red and blue pixels R1and B is adjacent to its associated subset S2. Furthermore, as for, theblue pixel B, its division pattern (i.e., a pattern that divides eachpixel into multiple subpixels) is horizontally inverted compared to thatof a pixel in any other color so that its bright subpixel is adjacent(i.e., located closer than its dark subpixels) to the subset S2.According to the division pattern adopted, it could sometimes bedifficult to make every luminance-lending bright subpixel adjacent to asubset of the second type (i.e., a subset to be a luminance borrower).However, if mutually different division patterns are adopted for a pixelrepresenting a particular primary color (e.g., a pixel including aluminance-lending subpixel) and for the other pixels, respectively,every luminance-lending bright subpixel can be adjacent to a subset ofthe second type.

Optionally, instead of inverting the division pattern of the blue pixelB, the bright and dark subpixels could be interchanged with each otheronly for the blue pixel B as shown in FIGS. 26 and 27. In this manner,even if the correlation between the luminance ranking and the mutuallydifferent shapes of multiple subpixels in a pixel representing aparticular primary color (e.g., a pixel including a luminance-lendingsubpixel) is different from the other pixels, every luminance-lendingbright subpixel can be adjacent to a subset of the second type. FIG. 28illustrates what subpixels are lit in a situation where a vertical whiteline is displayed on a black background using the subsets S2. ComparingFIGS. 28 and 25 to each other, it can be seen that the white line alsolooks thinner in such a situation, too.

Furthermore, not both of the luminance-lending bright subpixels of thefirst red and blue pixels R1 and B need to be adjacent to the subset S2.Instead, the subset S2 can also borrow a luminance from a brightsubpixel that is not adjacent to itself as shown in FIG. 29. In theexample illustrated in FIG. 29, each bright subpixel of the first redpixel R1 is adjacent to its associated subset S2 but no bright subpixelof the blue pixel B is adjacent to any subset S2.

FIG. 30 illustrates what subpixels are lit by lending and borrowing aluminance as shown in FIG. 29. As can be seen from FIG. 30, not onlyentire pixels (i.e., both of their first and second subpixels) in eachsubset S2 on the column C3 but also some subpixels on the columns C2 andC4 are lit so that the rendering processing for lending a luminance iscarried out on a subpixel-by-subpixel basis. Unlike the examplesillustrated in FIGS. 23 and 28, however, the lighted subpixels in eachsubset S1 include not just ones that are adjacent to its associatedsubset S2 but also ones that are not adjacent to the subset S2.Nevertheless, even if a luminance is lent and borrowed as shown in FIGS.29 and 30, the decrease in resolution can still be less significant thana situation where a luminance is lent and borrowed on a pixel-by-pixelbasis as shown in FIGS. 24 and 25. Naturally, to enhance the effect ofchecking the decrease in resolution, it is preferred that everyluminance-lending bright subpixel be adjacent to a luminance-borrowingsubset S2 as shown in FIGS. 22 and 23 or in FIGS. 27 and 28.

Such an effect will be described more specifically with reference toFIGS. 31 through 35. FIGS. 31, 32 and 33 illustrate the contours of thewhite line to be seen in the lighting states shown in FIGS. 25, 28 and30, respectively. On the other hand, FIG. 34 illustrates, incombination, the contours O4 and O5 that are shown in FIGS. 31 and 32,respectively, while FIG. 35 illustrates, in combination, the contours O4and O6 that are shown in FIGS. 31 and 33, respectively. FIGS. 31 through35 also show the centerline of the column C3.

Comparing the results shown in FIGS. 31 and 32 to each other byreference to FIG. 34, it can be seen that the white line displayed looksthinner by lending and borrowing a luminance on a subpixel-by-subpixelbasis rather than by doing that on a pixel-by-pixel basis. Specifically,supposing the width of a column of subsets is W, the white line to beseen in a situation where a luminance is lent and borrowed on apixel-by-pixel basis will be approximately 1.7 W, but the one to be seenin a situation where a luminance is lent and borrowed on asubpixel-by-subpixel basis will be approximately 1.3 W as shown in FIG.34. The same can be said even if the results shown in FIGS. 31 and 33are compared to each other by reference to FIG. 35. Consequently, bycarrying out the rendering processing on a subpixel-by-subpixel basis,the decrease in resolution can be much less significant, and the displayoperation can get done far more smoothly and with much higherdefinition, compared to a situation where the rendering processing iscarried out on a pixel-by-pixel basis.

It should be noted that according to this preferred embodiment, thesubset S2 does not always have to borrow a luminance from both of thebright subpixels of the first red pixel R1 and the blue pixel B. Forexample, each subset S2 may borrow a luminance from only the brightsubpixel of the first red pixel R1 belonging to its associated subset S1but does not need to borrow a luminance from the bright subpixel of theblue pixel B as shown in FIGS. 36 and 37. In that case, it is shown inFIG. 38 what subpixels are lit in a situation where a vertical whiteline is displayed on a black background using the subsets S2. As can beseen from FIG. 38, not only entire pixels belonging to every subset S2on the column C3 but also some subpixels belonging to each subset S1 onthe column C4 are lit, but all subpixels belonging to every subset S1 onthe column C2 are not lit.

The following Tables 3 and 4 and FIG. 39 show how the Y values and xychromaticity values of respective pixels and the Y values (i.e.,luminance values), xy chromaticity values and color temperatures of thecolors white represented by the subsets S1 and S2 change before andafter the rendering processing described above is carried out.

TABLE 3 Before render- ing Y x y Y(w) x(w) y(w) Tc(w)/K S1 R1 7.9 0.65810.3219 56.0 0.3340 0.2715 5360 Ye 43.1 0.4637 0.5248 B 5.0 0.1471 0.0502S2 R2 7.9 0.6581 0.3219 44.0 0.2842 0.3714 7529 G 21.3 0.2521 0.6579 C14.8 0.152 0.2404 total 100.0 100.0

TABLE 4 After rendering Y x y Y(w) x(w) y(w) Tc(w)/K S1 R1 5.4 (68%)0.6581 0.3219 53.5 0.3211 0.2695 6468 Ye 43.1 0.4637 0.5248 B  5.00.1471 0.0502 S2 R2  7.9 0.6581 0.3219 46.5 0.3074 0.2683 6504 G 21.30.2521 0.6579 C 14.8 0.152 0.2404 (R1) 2.5 (32%) 0.6581 0.3219 total100.0  100.0

As can be seen from Tables 3 and 4 and FIG. 39, by carrying out therendering processing (in which the first red pixel R1 in each subset S1lends 32% of its own luminance to its associated subset S2 as shown inTable 4), the differences in luminance, chromaticity and colortemperature between the respective colors white represented by thesubsets S1 and S2 decreases.

It should be noted that the division pattern of each pixel (includingthe pixel division number and the shapes of subpixels) does not have tobe what has already been described but could be any of various patternsas shown in FIGS. 40( a) through 40(f). Specifically, the subpixels mayhave rectangular shapes as shown in FIGS. 40( a) and 40(f) ortrapezoidal shapes as shown in FIGS. 40( b), 40(c) and 40(d) ortriangular shapes as shown in FIG. 40( e), for example.

Also, in this description, when the relative positions of aluminance-lending bright subpixel and a luminance-borrowing subset aredetermined, it is taken into consideration which of two portions of abright subpixel, which are defined by drawing a centerline that dividesa given pixel equally, has the greater area, and that bright subpixel issaid to be “adjacent” to a subset that is located in contact with thatportion of the bright subpixel with the greater area. For instance, inthe example illustrated in FIG. 41, a portion of the bright subpixel onthe left-hand side of the centerline CL1 has the larger area than theother portion thereof on the right-hand side of the centerline CL1, anda portion of the bright subpixel over the centerline CL2 has the largerarea than the other portion thereof under the centerline CL2. That iswhy the bright subpixel shown in FIG. 41 is said to be adjacent to asubset on the left-hand side of the pixel and to a subset right over thepixel. Also, in the examples illustrated in FIGS. 40( a), 40(c), 40(d)and 40(e), the bright subpixel is adjacent to a subset on the left-handside of the pixel. In the example illustrated in FIG. 40( b), the brightsubpixel is adjacent to a subset on the left-hand side of the pixel andto a subset right over the pixel. And in the example illustrated in FIG.40( f), the bright subpixel is adjacent to a subset on the left-handside of the pixel and to a subset right under the pixel.

Embodiment 3

FIG. 42 illustrates an arrangement of pixels for an LCD(multi-primary-color liquid crystal display device) 300 as a thirdspecific preferred embodiment of the present invention. As shown in FIG.42, the LCD 300 includes red pixels R representing the color red, greenpixels G representing the color green, blue pixels B representing thecolor blue, cyan pixels C representing the color cyan, magenta pixels Mrepresenting the color magenta, and yellow pixels Ye representing thecolor yellow. These pixels can form a number of subsets S1, eachincluding cyan, magenta and yellow pixels C, M and Ye, and a number ofsubsets S2, each including red, green and blue pixels R, G and B. Inthis preferred embodiment, rows of pixels in which cyan, magenta andyellow pixels C, M and Ye are arranged cyclically and rows of pixels inwhich red, green and blue pixels R, G and B are arranged cyclicallyalternate with each other in the column direction. Thus, a number ofsubsets S1 or S2 of the same type are arranged continuously in the rowdirection, while these two different types of subsets S1 and S2 arearranged alternately in the column direction.

FIGS. 43 and 44 schematically illustrate how to lend and borrow aluminance in this LCD 300. As shown in FIGS. 43 and 44, each subset S2borrows a luminance from respective bright subpixels of cyan, magentaand yellow pixels C, M and Ye belonging to its associated subsets S1.More specifically, each subset S2 not only borrows a luminance from thebright subpixels of cyan and yellow pixels C and Ye belonging to asubset S1 that is located on one side (i.e., over or under) of thesubset S2 but also borrows a luminance from the bright subpixel of amagenta pixel M belonging to a subset S1 that is located on the otherside. That is to say, in the LCD 300 of this preferred embodiment, anarbitrary subset of the second type borrows a luminance from both of twosubsets of the first type that are adjacent to itself on one and theother sides thereof in a predetermined direction.

The following Tables 5 and 6 and FIGS. 45 and 46 show how the Y valuesand xy chromaticity values of respective pixels and the Y values (i.e.,luminance values), xy chromaticity values and color temperatures of thecolors white represented by the subsets S1 and S2 change before andafter the rendering processing described above is carried out.

TABLE 5 Before render- ing Y x y Y(w) x(w) y(w) Tc(w)/K S1 C 13.4 0.16000.2800 58.1 0.3106 0.3298 6322 M 11.2 0.3200 0.1720 Ye 33.5 0.43000.5300 S2 R 11.3 0.6300 0.3150 41.9 0.2703 0.2479 16309 G 25.0 0.24000.6280 B 5.6 0.1450 0.0600 total 100.0 100.0

TABLE 6 After rendering Y x y Y(w) x(w) y(w) Tc(w)/K S1 R1 11.5 (86%) 0.1600 0.2800 50.0 0.3160 0.3298 6322 Ye 9.6 (86%) 0.3200 0.1720 B 28.8(86%)  0.4300 0.5300 S2 R 11.3 0.6300 0.3150 50.0 0.2761 0.2583 13135 G25.0 0.2400 0.6280 B  5.6 0.1450 0.0600 (C) 1.9 (14%) 0.1600 0.2800 (M)1.6 (14%) 0.3200 0.1720 (Ye) 4.7 (14%) 0.4300 0.5300 total 100.0  100.0

Before the rendering processing is carried out, the luminances,chromaticity values and color temperatures of the colors whiterepresented by the subsets S1 and S2 are quite different from each otheras can be seen from Table 5 and FIGS. 45 and 46. However, after therendering processing has been carried out (the cyan, magenta and yellowpixels C, M and Ye of the subset S1 lend 14% of their own luminance tothe subset S2 as can be seen from Table 6), the luminances of the colorswhite represented by the subsets S1 and S2 exactly agree with each otherand their differences in chromaticity and color temperature have alsodecreased as can be seen from Table 6 and FIGS. 45 and 46.

FIG. 47 illustrates what subpixels need to be lit to display ahorizontal white line on a black background using the subsets S2. As canbe seen from FIG. 47, not only entire pixels (i.e., both of their firstand second subpixels) in each subset S2 on the row L2 but also somesubpixels on the rows L1 and L3 are lit so that the rendering processingfor lending a luminance is carried out on a subpixel-by-subpixel basis.

For the purpose of comparison, it will be described what pixels are litin a situation where the rendering processing is carried out on amulti-primary-color liquid crystal display device in which no pixel isdivided into multiple subpixels. For example, if the renderingprocessing in which each subset S2 borrows a luminance from the cyan,magenta and yellow pixels C, M and Ye of its associated subset S1 hasbeen carried out as shown in FIG. 48, lighted pixels will be as shown inFIG. 49. As can be seen from FIG. 49, not only all pixels in each subsetS2 on the row L2 but also all pixels in each subset S1 on the row L1 arelit, and the rendering processing for lending a luminance has beencarried out on a pixel-by-pixel basis. And comparing FIGS. 47 and 49 toeach other, it can be seen easily that the white line displayed can lookthinner, and the display operation can get done more smoothly and withhigher definition, by lending and borrowing a luminance on asubpixel-by-subpixel basis as is done in this preferred embodiment.

In the example illustrated in FIG. 44, the bright subpixels of each setof cyan, magenta and yellow pixels C, M and Ye that lend their luminanceare all adjacent to its associated subset S2. Instead, the subset S2 canalso borrow a luminance from a bright subpixel that is not adjacent toitself as shown in FIG. 50. In the example illustrated in FIG. 50,looking at a certain subset S2, either the respective bright subpixelsof the cyan and yellow pixels C and Ye or that of the magenta pixel Mare/is adjacent to the subset S2 but the other subpixel(s) is/are not.

FIG. 51 illustrates what subpixels are lit by lending and borrowing aluminance as shown in FIG. 50. As can be seen from FIG. 51, not onlyentire pixels (i.e., both of their first and second subpixels) in eachsubset S2 on the row L2 but also some subpixels in its associated subsetS1 on the row L1 are lit so that the rendering processing for lending aluminance is carried out on a subpixel-by-subpixel basis. Unlike theexample illustrated in FIG. 47, however, the lighted subpixels in eachsubset S1 include not just ones that are adjacent to its associatedsubset S2 but also ones that are not adjacent to the subset S2.Nevertheless, even if a luminance is lent and borrowed as shown in FIGS.50 and 51, the decrease in resolution can still be less significant thana situation where a luminance is lent and borrowed on a pixel-by-pixelbasis as shown in FIGS. 48 and 49. Naturally, to enhance the effect ofchecking the decrease in resolution, it is preferred that everyluminance-lending bright subpixel be adjacent to a luminance-borrowingsubset S2 as shown in FIGS. 44 and 47.

Embodiment 4

FIG. 52 illustrates an arrangement of pixels for an LCD(multi-primary-color liquid crystal display device) 400 as a fourthspecific preferred embodiment of the present invention. As shown in FIG.52, the LCD 400 includes red pixels R representing the color red, greenpixels G representing the color green, blue pixels B representing thecolor blue, cyan pixels C representing the color cyan, and yellow pixelsYe representing the color yellow. These pixels can form a number ofsubsets S1, each including red, green and cyan pixels R, G and C, and anumber of subsets S2, each including blue and yellow pixels B and Ye. Inthis preferred embodiment, cyan, green, red, yellow and blue pixels C,G, R, Ye and B are cyclically arranged in this order within the same rowso that the subsets S1 and S2 alternate with each other in the rowdirection.

FIGS. 53 and 54 schematically illustrate how to lend and borrow aluminance in this LCD 400. As shown in FIGS. 53(a) and 54, each subsetS2 borrows a luminance from the bright subpixel of the red pixel Rbelonging to its associated subset S1. In addition, as shown in FIGS.53( b) and 54, each subset S1 borrows a luminance from the brightsubpixel of the blue pixel B belonging to its associated subset S2. Inthe LCDs 100, 200 and 300 of the first, second and third preferredembodiments described above, one of the two different types of subsetsborrows a luminance from the other type of subset one-sidedly. In theLCD 400 of this preferred embodiment, however, the two different typesof subsets mutually lend and borrow a luminance to/from each other.Specifically, in the example illustrated in FIG. 53( a), the subset S1is the “first type of subset” to lend a luminance, while the subset S2is the “second type of subset” to borrow a luminance. Conversely, in theexample illustrated in FIG. 53( b), the subset S2 is the “first type ofsubset” to lend a luminance, while the subset S1 is the “second type ofsubset” to borrow a luminance.

The following Tables 7 and 8 and FIGS. 55 and 56 show how the Y valuesand xy chromaticity values of respective pixels and the Y values (i.e.,luminance values), xy chromaticity values and color temperatures of thecolors white represented by the subsets S1 and S2 change before andafter the rendering processing described above is carried out.

TABLE 7 Before render- ing Y x y Y(w) x(w) y(w) Tc(w)/K S1 R 12.5 0.66000.3235 49.8 0.3305 0.3818 5567 G 21.1 0.2578 0.6622 C 16.2 0.1567 0.2703S2 Ye 44.5 0.5198 0.0098 50.2 0.2913 0.2618 10285 B 5.7 0.0537 0.7994total 100.0 100.0

TABLE 8 After rendering Y x y Y(w) x(w) y(w) Tc(w)/K S1 (B) 0.97 (17%)0.0537 0.7994 49.9 0.3017 0.3423 6984 R 11.6 (93%) 0.6600 0.3235 G 21.10.2578 0.6622 C 16.2 0.1567 0.2703 S2 (R) 0.88 (7%)  0.6600 0.3235 50.10.3118 0.2840 7085 Ye 44.5 0.5198 0.0098 B  4.7 (83%) 0.0537 0.7994total 100.0  100.0

Before the rendering processing is carried out, the chromaticity valuesand color temperatures of the colors white represented by the subsets S1and S2 are quite different from each other as can be seen from Table 7and FIG. 56. However, after the rendering processing (in which the redpixel R of the subset S1 lends 7% of its own luminance to the subset S2and the blue pixel B of the subset S2 lends 17% of its own luminance tothe subset S1 as shown in Table 8) has been carried out, the differencesin chromaticity and color temperature between the colors whiterepresented by the subsets S1 and S2 have decreased as can be seen fromTable 8 and FIG. 56. In this example, as can be seen from Table 7 andFIG. 55, the luminances of their colors white agree with each other fromthe beginning between the subsets S1 and S2, and therefore, theluminance of the colors white hardly changes before and after therendering processing.

FIG. 57 illustrates what subpixels need to be lit to display a verticalwhite line on a black background using the subsets S2. As can be seenfrom FIG. 57, not only entire pixels (i.e., both of their first andsecond subpixels) in each subset S2 on the column C3 but also somesubpixels in its associated subset S1 on the column C2 are lit so thatthe rendering processing for lending a luminance is carried out on asubpixel-by-subpixel basis. FIG. 58 illustrates what subpixels need tobe lit to display a vertical white line on a black background using thesubsets S1. As can be seen from FIG. 58, not only entire pixels (i.e.,both of their first and second subpixels) in each subset S1 on thecolumn C2 but also some subpixels in its associated subset S2 on thecolumn C1 are lit so that the rendering processing for lending aluminance is carried out on a subpixel-by-subpixel basis. As can beseen, by lending and borrowing a luminance on a subpixel-by-subpixelbasis in this manner, the white line displayed can look thinner and thedisplay operation can get done more smoothly and with higher definition.

In the example illustrated in FIG. 54, the bright subpixel of each redpixel R that lends a luminance to its associated subset S2 is adjacentto that subset S2, and the bright subpixel of each blue pixel B thatlends a luminance to its associated subset S1 is adjacent to that subsetS1. However, each of the subsets S1 and S2 may borrow a luminance from abright subpixel that is not adjacent to itself as shown in FIG. 59.Specifically, in the example illustrated in FIG. 59, the bright subpixelof each red pixel R is not adjacent to its associated subset S2 and thatof each blue pixel B is not adjacent to its associated subset S1,either.

FIGS. 60 and 61 illustrate what subpixels will be lit when a luminanceis lent and borrowed as shown in FIG. 59. As can be seen from FIG. 60,not only entire pixels (i.e., both of their first and second subpixels)in each subset S2 on the column C3 but also some subpixels in itsassociated subset S1 on the column C2 are lit, and therefore, therendering processing for lending a luminance has also been carried outon a subpixel-by-subpixel basis. However, unlike the situation shown inFIG. 57, the lighted subpixels in the subsets S1 are not adjacent to anysubset S2. Also, as can be seen from FIG. 61, not only entire pixels(i.e., both of their first and second subpixels) in each subset S1 onthe column C2 but also some subpixels in its associated subset S2 on thecolumn C1 are lit, and therefore, the rendering processing for lending aluminance has also been carried out on a subpixel-by-subpixel basis.However, unlike the situation shown in FIG. 58, the lighted subpixels inthe subsets S2 are not adjacent to any subset S1.

Even if a luminance is lent and borrowed as shown in FIGS. 60 and 61,the decrease in resolution can still be less significant than asituation where a luminance is lent and borrowed on a pixel-by-pixelbasis. Naturally, to enhance the effect of checking the decrease inresolution, it is preferred that every luminance-lending bright subpixelbe adjacent to a luminance-borrowing subset as shown in FIGS. 54, 57 and58.

Embodiment 5

FIG. 62 illustrates an arrangement of pixels for an LCD(multi-primary-color liquid crystal display device) 500 as a fifthspecific preferred embodiment of the present invention. Just like theLCD 400 of the fourth preferred embodiment described above, the LCD 500includes red, green, blue, cyan and yellow pixels R, G, B, C and Ye, andcyan, green, red, blue and yellow pixels C, G, R, B and Ye arecyclically arranged in this order within the same row. In this preferredembodiment, however, a row of pixels is arranged so as to shift by ahalf pitch from each of two adjacent rows of pixels. That is why thesubsets S1 and S2 are arranged alternately not only in the row directionbut also in the column direction as well. In other words, the subsets S1and S2 are arranged so as to form a checkerboard pattern.

FIG. 63 schematically illustrates how to lend and borrow a luminance inthis LCD 500. As shown in FIG. 63, each subset S2 borrows a luminancefrom the bright subpixel of the red pixel R belonging to its associatedsubset S1. In addition, each subset S1 borrows a luminance from thebright subpixel of the blue pixel B belonging to its associated subsetS2.

FIG. 64 illustrates what subpixels need to be lit to display an obliquewhite line on a black background using the subsets S2. As can be seenfrom FIG. 64, not only entire pixels (i.e., both of their first andsecond subpixels) in each subset S2 but also some subpixels in itsassociated subset S1 are lit so that the rendering processing forlending a luminance is carried out on a subpixel-by-subpixel basis. FIG.65 illustrates what subpixels need to be lit to display an oblique whiteline on a black background using the subsets S1. As can be seen fromFIG. 65, not only entire pixels (i.e., both of their first and secondsubpixels) in each subset S1 but also some subpixels in its associatedsubset S2 are lit so that the rendering processing for lending aluminance is carried out on a subpixel-by-subpixel basis.

In the example illustrated in FIG. 63, a luminance is supposed to belent and borrowed between two subsets that are adjacent to each other inthe row direction. However, a luminance may also be lent and borrowedbetween two subsets that are adjacent to each other in the columndirection as shown in FIG. 66. The subpixels to be lit in a situationwhere a luminance is lent and borrowed as shown in FIG. 66 are shown inFIGS. 67 and 68. Specifically, FIG. 67 illustrates a situation where anoblique white line is displayed on a black background using the subsetsS2, while FIG. 68 illustrates a situation where an oblique white line isdisplayed on a black background using the subsets S1. As can be seenfrom FIGS. 67 and 68, not only entire pixels in one type of subset butalso some subpixels in the other type of subset are lit so that therendering processing for lending a luminance is carried out on asubpixel-by-subpixel basis.

Embodiment 6

FIG. 69 illustrates an arrangement of pixels for an LCD(multi-primary-color liquid crystal display device) 600 as a sixthspecific preferred embodiment of the present invention. Just like theLCD 100 of the first preferred embodiment described above, the LCD 600includes first and second red, green, blue, yellow and cyan pixels R1,R2, G, B, Ye and C. In this preferred embodiment, however, the firstred, yellow, blue, second red, green and cyan pixels R1, Ye, B, R2, Gand C are cyclically arranged in this order within the same row. Inaddition, according to this preferred embodiment, a row of pixels isarranged so as to shift by a half pitch from each of two adjacent rowsof pixels. That is why the subsets S1 and S2 are arranged alternatelynot only in the row direction but also in the column direction as well.In other words, the subsets S1 and S2 are arranged so as to form acheckerboard pattern.

FIGS. 70 and 71 schematically illustrate how to lend and borrow aluminance in this LCD 600. As shown in FIGS. 70 and 71, each subset S2borrows a luminance from the respective bright subpixels of the firstred and blue pixels R1 and B belonging to its associated subset S1.

FIG. 72 illustrates what subpixels need to be lit to display an obliquewhite line on a black background using the subsets S2. As can be seenfrom FIG. 72, not only entire pixels (i.e., both of their first andsecond subpixels) in each subset S2 but also some subpixels in itsassociated subset S1 are lit so that the rendering processing forlending a luminance is carried out on a subpixel-by-subpixel basis.

In the example illustrated in FIGS. 70 and 71, a luminance is supposedto be lent and borrowed between two subsets that are adjacent to eachother in the column direction. However, a luminance may also be lent andborrowed between two subsets that are adjacent to each other in the rowdirection as shown in FIGS. 73 and 74. Specifically, in the exampleillustrated in FIGS. 70 and 71, each subset S2 borrows a luminance fromthe respective bright subpixels of the first red and blue pixels R1 andB belonging to its adjacent subset S1 in the column direction. On theother hand, in the example illustrated in FIGS. 73 and 74, each subsetS2 borrows a luminance from the respective bright subpixels of the firstred and blue pixels R1 and B belonging to its adjacent subset S1 in therow direction. The subpixels to be lit in a situation where a luminanceis lent and borrowed as shown in FIGS. 73 and 74 are shown in FIG. 75.Specifically, FIG. 75 illustrates a situation where an oblique whiteline is displayed on a black background using the subsets S2. As can beseen from FIG. 75, not only entire pixels (i.e., both of their first andsecond subpixels) in one type of subset S2 but also some subpixels inthe other type of subset S1 are lit so that the rendering processing forlending a luminance is carried out on a subpixel-by-subpixel basis.

Next, it will be described what driving method is preferably adopted tominimize a “flicker” on the screen. In a typical LCD, the voltageapplied to the liquid crystal layer of a pixel is set to be an ACvoltage (such a method is sometimes called an “AC driving method”) tocope with a reliability problem. That is to say, the applied voltage isdefined so that a pixel electrode and a counter electrode invert theirpotential levels at regular time intervals and that the electric fieldapplied to the liquid crystal layer inverts its direction (i.e., thedirection of electric lines of force) at regular time intervals. In atypical LCD in which the counter electrode and pixel electrodes arearranged on two different substrates, the electric field applied to theliquid crystal layer inverts its direction from toward the light sourceto toward the viewer, and vice versa.

The interval at which the electric field applied to the liquid crystallayer inverts its direction is typically 33.333 ms, which is twice aslong as one frame period of 16.667 ms, for example. That is to say, in aliquid crystal display device, every time a picture (i.e., an imageframe) is presented, the electric field applied to the liquid crystallayer inverts its direction. For that reason, in presenting a stillpicture, unless the electric field intensities (or applied voltages)exactly match each other between the two electric field directions(i.e., if the electric field changes its intensity every time it changesits direction), the luminance of each pixel will change with such avariation in electric field intensity, thus producing a flicker on thescreen.

In other words, to minimize such a flicker, the electric fieldintensities (or applied voltages) in those two electric field directionsneed to exactly match each other. In LCDs to be mass-produced on anindustrial basis, however, it is difficult to exactly match the electricfield intensities in those two directions. That is why they try tominimize the flicker by arranging pixels that have mutually oppositeelectric field directions adjacent to each other within a display areabecause the luminances of the pixels would be spatially averaged in thatcase. Such a method is generally called either a “dot inversion drive”or a “line inversion drive”. It should be noted that these “inversiondrive” methods include not just the “one dot inversion” in which thepolarities are inverted on a pixel-by-pixel basis in a “checkerboardpattern” so to speak (i.e., every row AND every column) and the “oneline inversion” in which the polarities are inverted on a line-by-linebasis but also a “two-row, one-column dot inversion” in which thepolarities are inverted every other row and every column, and variousother patterns. Thus, any of those various methods is appropriatelyadopted as needed.

In the LCD 600 of this preferred embodiment, six different kinds ofpixels are arranged regularly as shown in FIG. 76 in the row direction(i.e., the direction in which a number of source lines are arranged at apredetermined pitch and which is identified by “SL” that means a sourceline direction in FIG. 76). That is why if the dot inversion drive wasadopted, every primary color but the color red would have an electricfield applied to the liquid crystal layer in the same direction alongthe row. In FIG. 76, the directions (or polarities) of the electricfield applied to the liquid crystal layer are identified by the positive(+) and negative (−) signs. That is to say, the (+) and (−) directionsare two opposite directions in which the electric field is applied tothe liquid crystal layer. In the example illustrated in FIG. 76, thepolarity of the green and blue pixels G and B is always negative (−) andthat of the cyan and yellow pixels C and Ye is always positive (+). Forthat reason, if a display operation is performed in a single color, theflicker will be seen easily.

On the other hand, if the line inversion drive is performed every othercolumn (i.e., if a two-source-line inversion drive is performed) asshown in FIG. 77, the direction (i.e., polarity) of the electric fieldwill be inverted for every primary color. In the example shown in FIG.77, each of the green, yellow and blue pixels G, Ye and B invert theirpolarity from positive (+) into negative (−) from left to right and thecyan pixels C invert their polarity from negative (−) into positive (+)from left to right. Consequently, the flicker can be minimized even if adisplay operation is performed in a single color.

As can be seen, in a situation where the subsets of the first and secondtypes are arranged alternately in a predetermined direction (which maybe either the row direction or the column direction) and pixels are alsoarranged within each subset in that direction, if the sum of the numberof pixels that form the first type of subset and that of pixels thatform the second type of subset is an even number (e.g., six in theexample shown in FIGS. 76 and 77), the electric field will be applied inthe same direction to the liquid crystal layer for each primary colorand a flicker will be produced easily when a display operation isconducted in a single color. That is why the direction of the electricfield applied to the liquid crystal layer of each pixel is preferablyinverted every other pixel in the direction in which the two differenttypes of subsets are arranged. Then, the direction of the electric fieldapplied to the liquid crystal layer can be inverted for every primarycolor and the flicker can be minimized.

In the example illustrated in FIG. 77, the bright subpixels are notarranged in a checkerboard pattern, and the bright subpixels changetheir positions within pixels every other column in the row direction.That is to say, the correlation between the luminance ranking ofsubpixels and the arrangement of subpixels in the column directionchanges every two columns in the row direction. Naturally, even if theinversion drive is performed as shown in FIG. 77, the bright subpixelsmay also be arranged in a checkerboard pattern. However, in a situationwhere a configuration in which a storage capacitor is provided for eachof multiple subpixels and a different effective voltage is applied toeach subpixel by capacitance division is adopted as shown in FIG. 4 andwhere the two-source-line inversion drive is adopted, the brightsubpixels preferably change their positions within pixels every othercolumn in the row direction as shown in FIG. 77. This is because such anarrangement is easier to realize.

FIGS. 78 and 79 illustrate how a luminance is lent and borrowed in thearrangement shown in FIG. 77. As shown in FIGS. 78 and 79, each subsetS2 borrows a luminance from the bright subpixels of first red and bluepixels R1 and B belonging to its associated subset S1.

FIG. 80 illustrates what subpixels need to be lit to display an obliquewhite line on a black background using the subsets S2. As can be seenfrom FIG. 80, not only entire pixels (i.e., both of their first andsecond subpixels) in each subset S2 but also some subpixels in itsassociated subset S1 are lit so that the rendering processing forlending a luminance is carried out on a subpixel-by-subpixel basis.

As described above for the first through sixth preferred embodiments ofthe present invention, the multi-primary-color liquid crystal displaydevice of the present invention performs rendering processing forlending and borrowing a luminance on a subpixel-by-subpixel basis,thereby getting a display operation done with higher definition with thedecrease in resolution minimized. It should be noted that the number ofprimary colors to be used by the multi-primary-color liquid crystaldisplay device of the present invention for display purposes, the numberand kinds of pixels included in each subset, and the specificarrangements of respective subsets and pixels are never limited to theones that have already been described as examples for the first throughsixth preferred embodiments of the present invention.

INDUSTRIAL APPLICABILITY

The multi-primary-color liquid crystal display device of the presentinvention can get a display operation done far more smoothly and withmuch higher definition than a conventional device. The present inventionis broadly applicable to any multi-primary-color liquid crystal displaydevice in general that conducts a display operation in four or moreprimary colors.

1. A multi-primary-color liquid crystal display device for conducting adisplay operation in at least four primary colors, the device comprisinga plurality of pixels that form at least two different types of subsets,wherein the device has the ability to perform rendering processing inwhich at least one of the plurality of pixels that form a first one ofthe at least two different types of subsets lends a luminance to asecond type of subset, and wherein each of the plurality of pixelsincludes a first subpixel and a second subpixel that could have mutuallydifferent luminances, and wherein the second type of subset borrows aluminance from one of the first and second subpixels of the at least onepixel that has the higher luminance.
 2. The multi-primary-color liquidcrystal display device of claim 1, wherein the subpixel that has thehigher luminance in the at least one pixel and that lends a luminance tothe second type of subset is adjacent to the second type of subset. 3.The multi-primary-color liquid crystal display device of claim 2,wherein in dividing each of the plurality of pixels into the first andsecond subpixels, a pattern applied to a pixel representing a particularprimary color is different from a pattern applied to another pixel. 4.The multi-primary-color liquid crystal display device of claim 3,wherein the pixel representing the particular primary color includes asubpixel that lends a luminance to the second type of subset.
 5. Themulti-primary-color liquid crystal display device of claim 2, whereinthe first and second subpixels have mutually different shapes, andwherein a correlation between the luminance ranking of the first andsecond subpixels and the shapes of the first and second subpixels in thepixel representing the particular primary color is different fromanother pixel.
 6. The multi-primary-color liquid crystal display deviceof claim 5, wherein the pixel representing the particular primary colorincludes the subpixel that lends a luminance to the second type ofsubset.
 7. The multi-primary-color liquid crystal display device ofclaim 1, wherein a plurality of subsets of the first type and aplurality of subsets of the second type are arranged in matrix.
 8. Themulti-primary-color liquid crystal display device of claim 7, whereinthe first type of subsets and the second type of subsets are arrangedalternately in a predetermined direction, and wherein an arbitrary oneof the subsets of the second type borrows a luminance from one of thetwo subsets of the first type that are adjacent to itself on one and theother sides thereof, respectively, in the predetermined direction. 9.The multi-primary-color liquid crystal display device of claim 7,wherein the first type of subsets and the second type of subsets arearranged alternately in a predetermined direction, and wherein anarbitrary one of the subsets of the second type borrows a luminance fromboth of the two subsets of the first type that are adjacent to itself onone and the other sides thereof, respectively, in the predetermineddirection.
 10. The multi-primary-color liquid crystal display device ofclaim 7, wherein each of the plurality of pixels includes a liquidcrystal layer and a plurality of electrodes for applying an electricfield to the liquid crystal layer, and wherein the subsets of the firsttype and the subsets of the second type are alternately arranged in apredetermined direction, and wherein the pixels included in each saidsubset of the first type and the pixels included in each said subset ofthe second type are also arranged in the predetermined direction withintheir subset, and wherein the sum of the number of pixels included ineach said subset of the first type and that of pixels included in eachsaid subset of the second type is an even number, and wherein thedirection of the electric field applied to the liquid crystal layer ofeach said pixel inverts every two pixels in the predetermined direction.11. The multi-primary-color liquid crystal display device of claim 1,wherein the at least four primary colors include red, green and blue.12. The multi-primary-color liquid crystal display device of claim 11,wherein the at least four primary colors further include yellow andcyan.
 13. The multi-primary-color liquid crystal display device of claim12, wherein one of the first and second types of subsets includes afirst red pixel representing the color red, a blue pixel representingthe color blue, and a yellow pixel representing the color yellow, whilethe other type of subset includes a second red pixel representing thecolor red, a green pixel representing the color green, and a cyan pixelrepresenting the color cyan.
 14. The multi-primary-color liquid crystaldisplay device of claim 12, wherein one of the first and second types ofsubsets includes a red pixel representing the color red, a green pixelrepresenting the color green, and a cyan pixel representing the colorcyan, while the other type of subset includes a blue pixel representingthe color blue and a yellow pixel representing the color yellow.
 15. Themulti-primary-color liquid crystal display device of claim 12, whereinthe at least four primary colors further include magenta.
 16. Themulti-primary-color liquid crystal display device of claim 15, whereinone of the first and second types of subsets includes a red pixelrepresenting the color red, a green pixel representing the color green,and a blue pixel representing the color blue, while the other type ofsubset includes a cyan pixel representing the color cyan, a magentapixel representing the color magenta, and a yellow pixel representingthe color yellow.
 17. The multi-primary-color liquid crystal displaydevice of claim 1, wherein the rendering processing is carried out sothat a difference in luminance, chromaticity and/or color temperaturebetween respective colors white represented by the first and secondtypes of subsets decreases compared to a situation where the renderingprocessing is not carried out.